Package org.apache.druid.segment.join.lookup

Class LookupJoinable

java.lang.Object
org.apache.druid.segment.join.lookup.LookupJoinable
All Implemented Interfaces:
Joinable, ReferenceCountedObjectProvider<Closeable>
public class LookupJoinable extends Object implements Joinable

  • Method Details

    • wrap

      public static LookupJoinable wrap(LookupExtractor extractor)

    • getAvailableColumns

      public List<String> getAvailableColumns()
      Description copied from interface: Joinable
      Returns the list of columns that this Joinable offers.
      Specified by:
      getAvailableColumns in interface Joinable

    • getCardinality

      public int getCardinality(String columnName)
      Description copied from interface: Joinable
      Returns the cardinality of "columnName", or Joinable.CARDINALITY_UNKNOWN if not known. May be used at query time to trigger optimizations. If not Joinable.CARDINALITY_UNKNOWN, this must match the cardinality of selectors returned by the ColumnSelectorFactory.makeDimensionSelector(org.apache.druid.query.dimension.DimensionSpec) method of this joinable's JoinMatcher.getColumnSelectorFactory() .
      Specified by:
      getCardinality in interface Joinable

    • getColumnCapabilities

      @Nullable public ColumnCapabilities getColumnCapabilities(String columnName)
      Description copied from interface: Joinable
      Returns capabilities for one of this Joinable's columns.
      Specified by:
      getColumnCapabilities in interface Joinable
      Parameters:
      columnName - column name
      Returns:
      capabilities, or null if the columnName is not one of this Joinable's columns

    • makeJoinMatcher

      public JoinMatcher makeJoinMatcher(ColumnSelectorFactory leftSelectorFactory, JoinConditionAnalysis condition, boolean remainderNeeded, Closer closer)
      Description copied from interface: Joinable
      Creates a JoinMatcher that can be used to implement a join onto this Joinable.
      Specified by:
      makeJoinMatcher in interface Joinable
      Parameters:
      leftSelectorFactory - column selector factory that allows access to the left-hand side of the join
      condition - join condition for the matcher
      remainderNeeded - whether or not JoinMatcher.matchRemainder() will ever be called on the matcher. If we know it will not, additional optimizations are often possible.
      closer - closer that will run after join cursor has completed to clean up any per query resources the joinable uses
      Returns:
      the matcher

    • getMatchableColumnValues

      public Joinable.ColumnValuesWithUniqueFlag getMatchableColumnValues(String columnName, boolean includeNull, int maxNumValues)
      Description copied from interface: Joinable
      Returns all matchable values from a particular column along with a flag to tell if they are all unique in the column. If the matchable values are greater than "maxNumValues" or if the column doesn't exists or doesn't supports this operation, returns an object with empty set for column values and false for uniqueness flag. The uniqueness flag will only be true if we've collected all matchable values in the column and found that they're all unique. In all other cases it will be false. The returned set may be passed to InDimFilter. For efficiency, implementations should prefer creating the returned set with new TreeSet<String>(Comparators.naturalNullsFirst()}. This avoids a copy in the filter's constructor.
      Specified by:
      getMatchableColumnValues in interface Joinable
      Parameters:
      columnName - name of the column
      includeNull - whether null should be considered a matchable value. If true, this method returns all values that are present in the column. If false, this method returns all non-null values.
      maxNumValues - maximum number of values to return. If exceeded, returns an empty set with the "allUnique" flag set to false.

    • getCorrelatedColumnValues

      public Optional<InDimFilter.ValuesSet> getCorrelatedColumnValues(String searchColumnName, String searchColumnValue, String retrievalColumnName, long maxCorrelationSetSize, boolean allowNonKeyColumnSearch)
      Description copied from interface: Joinable
      Searches a column from this Joinable for a particular value, finds rows that match, and returns values of a second column for those rows. The returned set may be passed to InDimFilter. For efficiency, implementations should prefer creating the returned set with new TreeSet<String>(Comparators.naturalNullsFirst()}. This avoids a copy in the filter's constructor.
      Specified by:
      getCorrelatedColumnValues in interface Joinable
      Parameters:
      searchColumnName - Name of the search column. This is the column that is being used in the filter
      searchColumnValue - Target value of the search column. This is the value that is being filtered on.
      retrievalColumnName - The column to retrieve values from. This is the column that is being joined against.
      maxCorrelationSetSize - Maximum number of values to retrieve. If we detect that more values would be returned than this limit, return absent.
      allowNonKeyColumnSearch - If true, allow searchs on non-key columns. If this is false, a search on a non-key column returns absent.
      Returns:
      The set of correlated column values. If we cannot determine correlated values, return absent. In case either the search or retrieval column names are not found, this will return absent.

    • acquireReference

      public Optional<Closeable> acquireReference()
      Description copied from interface: ReferenceCountedObjectProvider
      This method increments a reference count and provides a Closeable that decrements the reference count when closed. The object returned by this method may or may not be thread-safe, it is best to check with the implementation.

      IMPORTANT NOTE: to fulfill the contract of this method, implementors must return a closeable to indicate that the reference can be acquired, even if there is nothing to close. Implementors should ideally avoid allowing this method to throw exceptions, but callers are responsible for closing the returned object should any operations on it throw exceptions.

      For callers: if this method returns non-empty, IT MUST BE CLOSED, else reference counts can potentially leak.

      Specified by:
      acquireReference in interface ReferenceCountedObjectProvider<Closeable>